Tennanah Lake Dam
Tennanah Lake Dam is a concrete dam located in Sullivan County, New York, built in 1914. It carries a Significant hazard potential classification and has a poor condition assessment.
About Tennanah Lake Dam
The primary purpose of Tennanah Lake Dam is recreation. The dam creates a reservoir used for recreational activities such as fishing, boating, and swimming. The dam is owned by Blue Mountain Associates;blue Mountain Associates (private). It impounds the Trout Brook near Tennanah Lake.
The dam stands 17 feet tall and stretches 41 feet across. Completed in 1914, the structure is over a century old.
This dam has a significant hazard potential classification, meaning that a failure could cause significant economic damage — flooding roads, bridges, or property downstream — but is not expected to result in loss of life. Its condition is rated poor, meaning the dam has recognized safety deficiencies that require remediation to address risks. The most recent inspection on record was 04/30/2025.
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Location
| State | New York |
| County | Sullivan |
| Nearest City | Tennanah Lake |
| River/Stream | Trout Brook |
| Coordinates | 41.89556, -74.98306 |
Physical Characteristics
| Dam Type | Concrete |
| NID Height | 17 ft |
| Dam Height | 17 ft |
| Dam Length | 41 ft |
| Year Completed | 1914 (112 years old) |
Ownership & Safety
| Purpose | Recreation |
| Owner | BLUE MOUNTAIN ASSOCIATES;BLUE MOUNTAIN ASSOCIATES |
| Owner Type | Private |
| Hazard Classification | Significant |
| Condition Assessment | Poor |
| Last Inspection | 04/30/2025 |
| Emergency Action Plan | No |
Identifiers
| NID ID | NY00339 |
| Federal ID | NY00339 |
| More Info | State Dam Safety Program |